Trusty robot helps us understand human social cues

Nexi the robot has been furthering social science and social robotics studies for the past several years. Photo by Mary Knox Merrill.

You’re not sure why, but you don’t trust that guy. You wouldn’t give him a buck because you’re pretty sure he wouldn’t return the favor. What is it about him? Can you put your finger on it?

Despite decades of searching, sci­en­tists have not been able to iden­tify the visual cues that help us deter­mine a stranger’s trust­wor­thi­ness. But humans are a pretty coop­er­a­tive bunch, so they must be gleaning some­thing from their non­verbal inter­ac­tions that explains who to trust and who to be wary of.

In an article soon to be pub­lished by the journal Psy­cho­log­ical Sci­ence, North­eastern Uni­ver­sity psy­chology pro­fessor David DeSteno and his col­leagues reveal the mys­tery. The research sug­gests that a dis­tinct set of silent cues — hand and face touching, for example, or arm crossing and leaning away — will betray humans’ bad intentions.

“There’s no one golden cue,” DeSteno said. “Con­text and coor­di­na­tion of move­ments are what matters.”

DeSteno’s team, which also included researchers from Cor­nell Uni­ver­sity and the Mass­a­chu­setts Insti­tute of Technology’s Media Lab, per­formed two exper­i­ments to unearth these find­ings. In the first exper­i­ment, which they called the exploratory phase, the researchers asked 86 North­eastern stu­dents to have either a face-​​to-​​face con­ver­sa­tion with another person or to engage in a web-​​based chat ses­sion. The live con­ver­sa­tions were video recorded and later coded for the amount of fid­geting the two par­tic­i­pants demonstrated.

After the ini­tial con­ver­sa­tion, the same two people were asked to play a prisoner’s dilemma game, with real money (albeit not much) at stake. Players could either be selfish and make a lot of money for them­selves, or they could be gen­erous — and hope their partner would too — for a smaller but com­munal profit. As might be expected, par­tic­i­pants were less gen­erous when they didn’t trust the other player.

Players who engaged in face-​​to-​​face con­ver­sa­tions were much better at picking out the less honest than those who only par­tic­i­pated in online chats. And if someone dis­played the tetrad of cues men­tioned above, that person was less likely to be gen­erous, and the partner would know it, even though she couldn’t say why.

In the second exper­i­ment, par­tic­i­pants con­versed with Nexi the Robot. Photo by Mary Knox Merrill.

“But the problem,” DeSteno said, “was that iden­ti­fying the exact cues that matter is dif­fi­cult. Humans express many things at once.”

In order to val­i­date the cue set, the team repeated the exper­i­ment. But this time, instead of talking with another North­eastern stu­dent, the par­tic­i­pants con­versed with a robot cre­ated by MIT’s Cyn­thia Breazeal — they call her Nexi.

Two exper­i­menters behind the prover­bial cur­tain con­trolled Nexi’s voice and move­ments. The par­tic­i­pants were unaware of the exper­i­menters and when they played the money game with Nexi later, they assumed they were playing with the robot. When Nexi touched its face and hands during the ini­tial inter­view, or leaned back or crossed its arms, people did not trust it to coop­erate in the game and kept their money to themselves.

By con­trol­ling the non­verbal cues par­tic­i­pants received, the Nexi exper­i­ment con­firms that the cue set revealed in the first exper­i­ment is not just a relic of over-​​fidgety par­tic­i­pants, DeSteno said. But more than that, he said these addi­tional results sug­gest that robots are capable of building trust and social bonds with humans. Our minds are willing to accept that fact and assign moral intent to tech­no­log­ical entities.

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